Parks in peril: are we loving our national parks to death?

You're scrambling up a rugged trail in Alaska?s Denali National Park. The trail is several kilometers long, so you figured most folks would skip it. You were wrong.

Hikers surround you, trampling plant life along the way. Halfway up, you encounter a cluster of majestic caribou grazing the mountainside. The scene would be serene--if not for the crowd of camera-toting tourists snapping away.

As millions of people head for the great outdoors this spring, National Parks around the country are feeling the pressure. "Our parks are really getting hammered by visitors," says Neil Poe, superintendent of Arches National Park in Utah. 'If we don't start managing the parks better, we'll destroy the reasons people come to them in the first place."

PREMIER PARK

Back in 1872, Congress created the first National Park--Yellowstone--to preserve and protect" its natural beauty and wildlife for the enjoyment of the public. Since then, people have been flocking to Yellowstone and the 52 other major parks to see the sights.

But today, the flow of visitors at many National Parks has gotten out of control. Last year, for example, about 275 million people visited our National Parks. Most of them arrived in cars.

All those cars emit a stew of pollutants, including carbon dioxide, carbon monoxide, and ozone ([O.sub.3]). When pollutants like ozone are present in Earth's lower atmosphere, they can harm animals and plants. At Yosemite National Park, for instance, the needles on the pine trees are yellowing-- "a sure sign of ozone damage," says park spokesperson Chris Fister.

Ozone also contributes to photochemical smog, a "fog" of pollutants produced by chemical reactions between sunlight and autoexhaust gases. Aside from being bad for animals' lungs, the dense smog can make snowcapped-mountain views disappear.

ACID RAIN

Another serious form of air pollution occurs when sulfur and nitrogen oxides from car exhaust and factory smokestacks enter the upper atmosphere. High in the stratosphere, these gases combine with moisture to form acid rain. The pollutants then shower down on park streams and rivers, harming--or even killing--aquatic animals and plants.

That's just a sampling of the chemical pollution that threatens our parks, says Yosemite's Fister. But there are other kinds of pollution too--like noise.

Take the Grand Canyon. About 800,000 people tour the Canyon by helicopter and plane each year. Tourists get a spectacular view, but some rangers suspect the noise may drive breeding birds away from their nests, or frighten deer away from their watering holes.

So far, says Mike Ebersole, chief pilot for the park service at the Grand Canyon, studies haven't been able to prove that noise is hurting wildlife in the long term. But it is annoying to humans.

"People write in and say they feel as if they're on the set of M*A*S*H because of all the helicopters," Ebersole says. In the 1980s, Congress passed a law saying that parks should preserve "the natural quiet." Right now, says Ebersole, "We're not complying with that law."

TOO MANY FEET

The view from the ground is even more troublesome, park rangers say. All those human visitors trampling on fragile plants and soil have caused massive erosion, the wearing away of soil. Desert soils are especially vulnerable, says Poe of Arches National Park.

In deserts, where water is scarce, plantlike organisms called lichens grow on the underside of rocks. The fungi and algae that make up lichens have a symbiotic relationship--that is, they live together as a single unit and help each other to survive.

As lichens grow they secrete acids that loosen bits of rock. These rock particles, together with the moisture-retaining lichens, form a cryptobiotic mat, the first thin layer of soil that desert plants need to grow. These mats form the base of the whole desert ecosystem, says Poe. If park visitors destroy the mats by clamoring over rocks, eventually no new plants will grow, he says.

PRESERVATIONS, PLEASE

What can we do to preserve our National Parks? One solution is to limit the number of people who can visit fragile areas, such as Delicate Arch, the breathtaking formation of cinnamon-colored sandstone at Arches National Park: One day, park officials say, you may have to make reservations just to get into a park.

"It's an unpopular concept, but at some point we're just going to have to consider limiting the use of the parks," says Dave Haskell, director of resource management at the Grand Canyon Border Patrol.

But others will surely resist. "We must not limit people's opportunity to visit [our parks]," says Viki Eggers of the West Yellowstone Chamber of Commerce. After all, Americans help pay for parks with their federal taxes, she says.

What do you think? Should the National Park Service restrict the number of visitors to parks? See what some of your peers say (left), then debate and decide. Can you think of other options for preserving the parks?